Clamp based lesion formation apparatus and methods configured to protect non-target tissue

ABSTRACT

Apparatus, systems and methods for forming lesions in target tissue and positioning an insulation element adjacent to non-target tissue.

BACKGROUND OF THE INVENTIONS

1. Field of Inventions

The present inventions relate generally to devices for performingtherapeutic operations on body tissue.

2. Description of the Related Art

There are many instances where therapeutic elements must be positionedadjacent to body tissue. One instance involves the formation oftherapeutic lesions to treat cardiac conditions such as atrialfibrillation, atrial flutter and arrhythmia. Therapeutic lesions, whichmay also be used to treat conditions in other regions of the body suchas the prostate, liver, brain, gall bladder, uterus, breasts, lungs andother solid organs, are typically formed by ablating tissue.

The present inventor has determined that lesion formation devices aresusceptible to improvement. For example, the present inventor hasdetermined that conventional lesion formation devices can be difficultto position and can damage non-target tissue near the tissue in whichthe therapeutic lesions are being formed. Conventional lesion formationapparatus can also roll in the direction of non-target tissue afterbeing properly positioned. In the context of epicardial pulmonary veinisolation, it is desirable to form lesions in cardiac tissue becauseablation of the pulmonary veins or pulmonary vein ostia can lead tostenosis. The present inventor has also determined that it would bedesirable to provide devices that more accurately focus tissuecoagulation energy during a lesion formation procedure in order toenhance the therapeutic effect, increase efficiency, and reduce thelikelihood that non-target tissue will be ablated.

SUMMARY OF THE INVENTIONS

An apparatus in accordance with one invention herein includes aninsulation element, defining an exterior surface, a lumen, and a slotthat extends from the lumen to the exterior surface such that there areexterior surface portions on opposite sides of the slot and the slotdefines a width that is less than the exterior surface portion widths,and an energy transmission element aligned with at least the portion ofthe slot at the exterior surface of the insulation element.

An apparatus in accordance with another invention herein, which may becarried by, or removably secured to, a clamp member, includes alongitudinally extending insulation element and a longitudinallyextending lesion formation region associated with the insulation elementsuch that there are insulation element side portions on opposite sidesof the lesion formation region and the side portion widths are greaterthan the lesion formation region width.

An apparatus in accordance with another invention herein includes a mainbody and a slot that is configured to receive a probe shaft with one ormore energy emission elements. The main body is preferably formed frommaterial that allows it to act as an insulation element.

There are a wide variety of advantages associated with the presentinventions. By way of example, but not limitation, and as described indetail below, the present inventions prevent damage to non-target tissuenear the target tissue in which the therapeutic lesions are beingformed.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed description of preferred embodiments of the inventions will bemade with reference to the accompanying drawings.

FIG. 1 is a side view of an electrophysiology probe positioning wrap inaccordance with a preferred embodiment of a present invention.

FIG. 2 is a section view taken along line 2-2 in FIG. 1.

FIG. 3 is a partial section view taken along line 3-3 in FIG. 1.

FIG. 4 is a plan view of a electrophysiology probe that may be used incombination with the positioning wrap illustrated in FIG. 1.

FIG. 5 is a section view showing the electrophysiology probe illustratedin FIG. 5 inserted through the positioning wrap illustrated in FIG. 1.

FIG. 6 is a section view taken along line 6-6 in FIG. 5.

FIG. 7 is a top view of a portion of the positioning wrap illustrated inFIG. 1 with the energy transmission element removed.

FIG. 8 is a perspective view showing a surgical system including thepositioning wrap apparatus illustrated in FIG. 1.

FIG. 9 is perspective view showing a continuous lesion formed around thepulmonary veins.

FIG. 10 is a side view of an electrophysiology probe positioning wrap inaccordance with a preferred embodiment of a present invention.

FIG. 11 is a section view taken along line 11-11 in FIG. 10.

FIG. 12 is a partial section view taken along line 12-12 in FIG. 10.

FIG. 12A is a section view of a hemostasis valve.

FIG. 13 is a side view of an electrophysiology probe positioning wrap inaccordance with a preferred embodiment of a present invention.

FIG. 14 is a section view taken along line 14-14 in FIG. 13.

FIG. 15 is a partial section view taken along line 15-15 in FIG. 13.

FIG. 16 is a side view of an electrophysiology probe positioning wrap inaccordance with a preferred embodiment of a present invention.

FIG. 17 is a section view taken along line 17-17 in FIG. 16.

FIG. 18 is a plan view of the positioning wrap illustrated in FIG. 16.

FIGS. 19A, 19C, 19E and 19G are top views of portions ofelectrophysiology probe positioning wraps in accordance with preferredembodiments of present inventions with the energy transmission elementsremoved.

FIGS. 19B, 19D, 19F and 19H are section views respectively taken alongline 19B-19B in FIG. 19A, line 19D-19D in FIG. 19C, line 19F-19F in FIG.19E and line 19H-19H in FIG. 19G.

FIG. 19I is a section view of an electrophysiology probe positioningwrap in accordance with a preferred embodiment of a present invention.

FIG. 20 is a side view of an electrophysiology probe positioning wrap inaccordance with a preferred embodiment of a present invention.

FIG. 21 is a section view taken along line 21-21 in FIG. 20.

FIG. 22 is a side view of the positioning wrap illustrated in FIG. 20 ina loop orientation.

FIG. 23 is a side view of an electrophysiology probe positioning wrap inaccordance with a preferred embodiment of a present invention.

FIG. 24 is a top view of a portion of the positioning wrap illustratedin FIG. 23.

FIG. 25 is a bottom view of a portion of the positioning wrapillustrated in FIG. 23.

FIG. 26 is a side view of the positioning wrap illustrated in FIG. 23 ina loop orientation.

FIG. 27 is a side view of an electrophysiology probe positioning wrap inaccordance with a preferred embodiment of a present invention.

FIG. 28 is a section view taken along line 28-28 in FIG. 27.

FIG. 29 is a partial side view of an electrophysiology probe positioningwrap in accordance with a preferred embodiment of a present invention.

FIG. 30 is a side view of a portion of an electrophysiology probepositioning wrap and an insulation sleeve in accordance with a preferredembodiment of a present invention.

FIG. 31 is a side view of a portion of an electrophysiology probepositioning wrap and an insulation sleeve in accordance with a preferredembodiment of a present invention.

FIG. 32 is a section view taken along line 32-32 in FIG. 31.

FIG. 32A is a section view of a positioning wrap in accordance with apreferred embodiment of a present invention.

FIG. 32B is a top view of a portion of a positioning wrap in accordancewith a preferred embodiment of a present invention.

FIG. 33 is a perspective view of a surgical system in accordance with apreferred embodiment of a present invention.

FIG. 34 is a plan view of a clamp in accordance with a preferredembodiment of a present invention.

FIG. 35 is a section view taken along line 35-35 in FIG. 34.

FIG. 36 is a top view of a portion of the clamp illustrated in FIG. 34.

FIG. 37 is a plan view of a tissue coagulation assembly in accordancewith a preferred embodiment of a present invention.

FIG. 38 is a side, partial section view of a portion of the tissuecoagulation assembly illustrated in FIG. 37.

FIG. 39 is a section view taken along line 39-39 in FIG. 38.

FIG. 40 is a section view taken along line 40-40 in FIG. 38.

FIG. 41 is a section view taken along line 41-41 in FIG. 38.

FIG. 42 is a section view taken along line 42-42 in FIG. 37.

FIG. 43 is a section view taken along line 43-43 in FIG. 37.

FIG. 44 is a section view taken along line 44-44 in FIG. 37.

FIG. 45 is a section view taken along line 45-45 in FIG. 37.

FIG. 46 is a perspective view of a surgical system in accordance with apreferred embodiment of a present invention.

FIG. 47 is a section view taken along line 47-47 in FIG. 46.

FIG. 48 is an end view of the insulation element illustrated in FIG. 46.

FIG. 49 is a bottom view of a portion of the tissue surgical systemillustrated in FIG. 46.

FIG. 50 is a plan view of a portion of the surgical probe illustrated inFIG. 46.

FIG. 51 is a section view taken along line 51-51 in FIG. 50.

FIG. 52 is a section view taken along line 52-52 in FIG. 50.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following is a detailed description of the best presently knownmodes of carrying out the inventions. This description is not to betaken in a limiting sense, but is made merely for the purpose ofillustrating the general principles of the inventions.

The detailed description of the preferred embodiments is organized asfollows:

I. Introduction

II. Exemplary Electrophysiology Probe Positioning Wraps Capable of BeingSecured Around an Organ

III. Exemplary Clamp Based Lesion Formation Apparatus

IV. Exemplary Probe Based Lesion Formation Apparatus The section titlesand overall organization of the present detailed description are for thepurpose of convenience only and are not intended to limit the presentinventions.

I. Introduction

This specification discloses a number of structures, mainly in thecontext of cardiac treatment, because the structures are well suited foruse with myocardial tissue. Nevertheless, it should be appreciated thatthe structures are applicable for use in therapies involving other typesof soft tissue. For example, various aspects of the present inventionshave applications in procedures concerning other regions of the bodysuch as the prostate, liver, brain, gall bladder, uterus, breasts,lungs, esophagus, and other solid organs.

Additionally, although the exemplary implementations are described belowin the context of lesion formation regions that transmit radio-frequencyenergy to tissue, either directly or by way of a conductive fluid, thepresent inventions are not so limited. Other lesion formation regions,such as those formed by laser arrays, ultrasonic transducers, microwaveelectrodes, and ohmically heated hot wires, may be employed withsuitably configured insulation elements. Lesion formation regions mayalso be formed with one or more cryotemperature devices, or needleprojections for chemical ablation (which are preferably about 1 to 2 mmin length), and combined with suitably configured insulation elements.

II. Exemplary Electrophysiology Probe Positioning Wraps Capable of BeingSecured Around an Organ

An electrophysiology probe positioning wrap (or “positioning wrap”) 100in accordance with one embodiment of a present invention is illustratedin FIGS. 1-3 and 5-7. The illustrated embodiment includes an insulationelement 102, an energy transmission element 104 and a connector device106 that may be used to position the longitudinal ends of the energytransmission element adjacent to one another. The insulation element102, which is provided with a probe lumen 108, may be used to hold anelectrophysiology probe 230 (FIG. 4) and to prevent coagulation ofnon-target tissue. The insulation element 102 also prevents rolling andslipping and facilitates the formation of a linear lesion. The exemplaryelectrophysiology probe 230 includes a probe body 232, a plurality ofelectrodes 234 (or other energy emission elements) carried on the distalportion of the probe body, a handle 236 at the proximal end of the probebody, and a pull wire 238 at the distal end of the probe body.

Tissue coagulation energy from the electrodes 234 is transferred to, andthrough, the energy transmission element 104 by electrically conductivefluid. To that end, the inner diameter of the probe lumen 108 isslightly greater than the outer diameter of the probe body 232. When theelectrophysiology probe 230 is inserted into one end of the positioningwrap 100 to such an extent that the distal end of the probe body 232reaches the other end (FIG. 5), a fluid transmission space 110 will bedefined between the probe body and the inner surface of the probe lumen108. The insulation element 102 also includes a fluid slot 112 thatextends from the fluid transmission space 110 to the energy transmissionelement 104. Preferably, the electrodes 234 will be carried on theelectrophysiology probe 230 such that the electrodes will, as a group,extend from one end of the fluid slot 112.

It should be noted that despite the fact that the energy transmissionelement 104 extends from one side of the insulation element 102 to theother, ablation is limited to the area adjacent to the fluid slot 112.This is because current tends to follow the path of least resistance toground potential, which in this case is from the electrodes 234, thoughthe slot 112, to the tissue.

The positioning wrap 100 also includes seals that prevent leakage fromthe fluid transmission space 110. In the embodiment illustrated in FIGS.1-3 and 5-7, fluidic seals 114 and 116 are formed in the insulationelement 102. The inner diameter of the fluidic seals 114 and 116 isslightly less than the outer diameter of the probe body 232. As such,the fluidic seals 114 and 116 will engage with probe body 232 and sealthe longitudinal ends of the fluid transmission space 110. The fluidicseals 114 and 116 are created by reducing the diameter of the probelumen 108 at the longitudinal ends of the insulation element 102. A pairof rings 118 helps to maintain the seals around the probe body 232.

In addition to the probe lumen 108, the exemplary positioning wrap 100is provided with fluid lumens 120 and 122 (FIGS. 2, 3 and 5). The fluidlumens 120 and 122, which are connected to one end of the probe lumen108, may be used for fluid ventilation when fluid is infused into thepositioning wrap 100 by way of the probe lumen, or may be used forinfusion when fluid is ventilated from the positioning wrap by way ofthe probe lumen. The probe lumen 108 and the fluid lumens 120 and 122are connected to respective tubes that are used to infuse and ventilatefluid to and from the lumens. Referring to FIGS. 1, 3 and 5, in theillustrated embodiment, the probe lumen 108 is connected to a tube 124that passes through an aperture 126 in the insulation element 102. Thefluid lumens 120 and 122 are connected to tubes 128 and 130 that extenddirectly into the fluid lumens by way of openings 132 and 134. The tubes128 and 130 are connected to a common tube 136 by a connector 138.Stopcocks 140 and 142 are provided on the ends of the tubes 124 and 136.

The surfaces of probe lumens in accordance with present invention may beconfigured such that they are smooth and continuous from one end toanother. As illustrated in FIGS. 6 and 7, however, the inner surface ofthe probe lumen 108 in the exemplary positioning wrap 100 includes aplurality of protrusions 144 and channels 146. The protrusions 144 andchannels 146 perform a variety of functions. For example, theprotrusions 144 and channels 146 reduce the amount of surface area thatmay come into contact with the probe body 232, thereby reducing theamount of friction that will be present as the probe body is fed into,and pulled out of, the positioning wrap 100. The protrusions 144 andchannels 146 also insure that fluid flow will not be restricted in thoseinstances where the probe lumen 108 collapses slightly. Other exemplarylumen surface configurations are discussed below with reference to FIGS.19A-19H.

Referring to FIGS. 1, 2 and 8, the exemplary connector device 106 is arelatively thin, flexible elongate device that includes a main portion148 and a pair of end portions 150 and 152. The main portion 148 issecured to the insulation element 102, preferably along the entirelength of the insulation element. The end portions 150 and 152, whichextend from the longitudinal ends of insulation element 102, may be usedto pull the lesion formation apparatus 100 into the orientationillustrated in FIG. 8 and then tied onto a knot 154 to hold the lesionformation apparatus in place. The end portions 150 and 152 may also beprovided with knots, beads, eyelets and/or any other closure mechanismthat can be used to hold the end portions (as well as the longitudinalends of the insulation element 102) in the orientation illustrated inFIG. 8.

The positioning wrap 100 and electrophysiology probe 230 may be employedin the exemplary surgical system 10 illustrated in FIG. 8, which mayalso include a fluid supply and control apparatus 300 and a power supplyand control apparatus 320. The fluid supply and control apparatus 300,which may be used to supply electrically conductive fluid to any of thedevices described herein that use such fluid, includes housing 302, afluid outlet port 304, and a fluid inlet port 306. The fluid outlet port304 may be coupled to the stopcock 140 (and, therefore, to the probelumen 108) by a connector tube 308, while the fluid inlet port 306 maybe coupled to the stopcock 142 (and, therefore, to the fluid lumens 120and 122) by a connector tube 310. An infusion pump capable of variableflow rates is one example of a suitable fluid supply and controlapparatus.

The power supply and control apparatus 320 includes an electrosurgicalunit (“ESU”) 322 that supplies and controls RF power. A suitable ESU isthe Model 4810A ESU sold by Boston Scientific Corporation of Natick,Mass., which is capable of supplying and controlling power on anelectrode-by-electrode basis. With respect to temperature sensing,temperature at the electrodes 234 may be determined by measuringimpedance at each electrode or by including temperature sensors on theprobe 230. The ESU 322 transmits energy to the electrodes 234 by way ofa cable 324 and a connector 326, which may be connected to a PC board inthe probe handle 236. The amount of power required to coagulate tissueranges from 5 to 150 W. Tissue coagulation energy emitted by theelectrodes 234 is returned through one or more indifferent electrodes328 that are externally attached to the skin of the patient with apatch, or one or more electrodes (not shown) that are positioned in theblood pool, and a cable 330. The cables 324 and 330 are configured to beconnected to differently sized connectors 332 and 334 on the ESU 322 inorder to prevent improper connections.

The positioning wrap 100 may be positioned around portions of organsduring lesion formation procedures performed with the surgical system10. For example, one method of treating focal atrial fibrillation withthe positioning wrap 100 involves the creation of transmural lesionsaround the pulmonary veins. Lesions may be created around the pulmonaryveins individually, in pairs, or, as is illustrated in FIG. 9, a singletransmural epicardial lesion L may be created around all four of thepulmonary veins PV. Such a lesion may be formed by positioning thepositioning wrap 100 around the pulmonary veins PV in the mannerillustrated in FIG. 8. The connector device 106 may be used to securethe longitudinal ends of the energy transmission element 104 in closeproximity to one another. Although there is a slight space between theends of the energy transmission element 104 in FIG. 8 in order to moreclearly show various elements of the illustrated embodiment, the endswould typically be in contact with one another or slightly overlap inactual use. Typically, the pull wire 238 at the distal end of the probebody 232 will have been pulled through the positioning wrap 100 prior toit being positioned around the pulmonary veins PV or other target tissuearea.

Once the positioning wrap 100 is in place, the probe body 232 may bepulled through the probe lumen 108 with the pull wire 238 until both ofthe fluidic seals 114 and 116 have engaged portions of the probe body.Alternatively, the probe body 232 may be pulled through the probe lumen108 prior to positioning the wrap 100 around the pulmonary veins PV orother target tissue area. The fluid transmission space 110 and fluidslot 112 are then filled with conductive fluid from the fluid supply andcontrol apparatus 300. The fluid may be continuously infused andventilated by way of the tubes 124, 128, 130, 308 and 310 or,alternatively, fluid flow may be stopped after the fluid transmissionspace 110 and slot 112 have been filled. Tissue coagulation energy isthen transmitted from the power supply and control apparatus 320 to one,some or all of the electrodes 234. The energy will flow through theconductive fluid and energy transmission element 104 to create a lesionin the vicinity of the fluid slot 112. Preferably, the electrodes 234will as a group be coextensive with the entire target tissue area. Inthose instances where the electrodes 234 are not coextensive with theentire target tissue area, the probe body 232 may be indexed after aportion of the lesion is formed by pulling on the pull wire 238 (orhandle 236) in order to move the electrodes 234 to another portion ofthe target tissue area. Tissue coagulation energy will then betransmitted from the power supply and control apparatus 320 to one, someor all of the electrodes 234 to form another portion of the lesion. Thisprocess will continue until the lesion is complete.

Although the present inventions are not limited to any particularmaterials, suitable materials for the insulation element 102 includeflexible polymer (elastomer) open and closed cell foams. In thoseinstances where open cell foams are used, the base member may include asealing skin (not shown) to prevent fluid absorption. Flexiblethermoplastics and thermoset polymers may also be employed. Materialsthat have a hardness rating of 25 to 35 (Shore A) are preferred. Inaddition to protecting adjacent tissue from the tissue coagulationenergy, the insulation element makes the positioning wrap 100 “onedirectional” in that energy will only be transferred through the slot112. Such an arrangement is more efficient than one in which the energytransfer can take place along the entire perimeter of the electrodes234.

Turning to the energy transmission element 104, a hydrophilic conductivepolymer film that is about 0.002 to 0.008 inch thick is one example of asuitable energy transmission element. Although the polymer film iselectrically non-conductive, the relatively small pores of this materialallow effective ionic transport in response to the applied RF field. Atthe same time, the relatively small pores prevent transfer ofmacromolecules through the material, so that pressure driven liquidperfusion is less likely to accompany the ionic transport, unlessrelatively high pressure conditions develop within positioning wrap.Hydro-Fluoro™ material, which is disclosed in U.S. Pat. No. 6,395,325,is one material that may be used. Materials such as nylons (with asoftening temperature above 100° C.), PTFE, PEI and PEEK that havemicropores created through the use of lasers, electrostatic discharge,ion beam bombardment or other processes may also be used. Such materialswould preferably include a hydrophilic coating. Nanoporous tomicroporous materials may also be fabricated by weaving a material (suchas nylon, polyester, polyethylene, polypropylene, hydrophiliccopolymers, expanded PTFE, fluorocarbon, glass, cotton, or other fiber)into a mesh having the desired pore size and porosity. Regeneratedcellulose membrane materials, typically used for blood oxygenation,dialysis or ultrafiltration, are other examples of suitable nanoporousmaterial for the energy transmission element 104.

Pore diameters smaller than about 1-10 nanometers retain macromolecules,but allow ionic transfer through the pores in response to the applied RFfield. With smaller pore diameters, pressure driven liquid perfusionthrough the pores is less likely to accompany the ionic transport,unless relatively high pressure conditions develop within the energytransmission element 104. Larger pore diameters (up to 8 μm) can also beused to permit ionic current flow across the membrane in response to theapplied RF field. With larger pore diameters, pressure driven fluidtransport across the energy transmission element 104 is much higher.Where a larger pore diameter is employed, thereby resulting insignificant fluid transfer (or “weeping”) through the energytransmission element 104, a saline solution having a sodium chlorideconcentration of about 0.9% weight by volume would be preferred. Suchweeping reduces impedance and tissue desiccation.

With respect to porosity, which represents the volumetric percentage ofthe energy transmission element 104 that is composed of pores and notoccupied by the casing material, the magnitude of the porosity affectselectrical resistance. Low-porosity materials have high electricalresistivity, whereas high-porosity materials have low electricalresistivity. The porosity of the energy transmission element 104 shouldbe at least 1% for epicardial applications employing a 1 to 5 μm porediameter.

The electrical resistivity of the energy transmission element 104 willhave a significant influence on lesion geometry and controllability.Low-resistivity (below about 500 ohm-cm) requires more RF power andresults in deeper lesions, while high-resistivity (at or above about 500ohm-cm) generates more uniform heating and improves controllability.Because of the additional heat generated by the increased resistivitywithin the energy transmission element 104, less RF power is required toreach similar surface tissue temperatures after the same interval oftime. Consequently, lesions generated with high-resistivity structuresusually have smaller depth. The electrical resistivity of the energytransmission element 104 can be controlled by specifying the pore sizeof the material, the porosity of the material, and the water adsorptioncharacteristics (hydrophilic versus hydrophobic) of the material. Adetailed discussion of these characteristics is found in U.S. Pat. No.5,961,513. A suitable electrical resistivity for epicardial lesionformation is about 1 to 3000 ohm-cm measured wet.

Turning to water absorption characteristics, hydrophilic materials aregenerally preferable because they possess a greater capacity to provideionic transfer of RF energy without significant liquid flow through thematerial.

The electrically conductive ionic fluid preferably possesses a lowresistivity to decrease ohmic loses, and thus ohmic heating effects,within the positioning wrap. The composition of the electricallyconductive fluid can vary. In the illustrated embodiment, the fluid is ahypertonic saline solution, having a sodium chloride concentration at ornear saturation, which is about 5% to about 25% weight by volume.Hypertonic saline solution has a relatively low resistivity of onlyabout 5 ohm-cm, as compared to blood resistivity of about 150 ohm-cm andmyocardial tissue resistivity of about 500 ohm-cm. Alternatively, theionic fluid can be a hypertonic potassium chloride solution. Withrespect to temperature and flow rate, a suitable inlet temperature forepicardial applications (the temperature will, of course, rise as heatis transferred to the fluid) is about 0 to 25° C. with a constant flowrate of about 2 to 10 ml/min.

One suitable material for the connector device 106 is thin (e.g. about0.005 inch to 0.025 inch) woven fabric ribbon. This material isrelatively soft and will not slice through tissue during use. Othersuitable materials include polymer films and cords. The main portion 148may be secured to the insulation element 102 with a flexible adhesive(not shown) such as polyurethane or a Polycin® and Vorite® mixture.

The overall dimensions of positioning wraps in accordance with thepresent inventions will, of course, depend on the intended application.In one exemplary implementation that is suitable for forming epicardiallesions around the pulmonary veins, the insulation element 102 is about15 cm to 30 cm in length. The aspect ratio, i.e. the width to thickness(or height) ratio, is about 2-3 to 1. Typically, in the orientationillustrated in FIG. 2, the width of the insulation element 102 is about7 mm to 20 mm and the thickness is about 3 mm to 10 mm. With respect tothe exemplary connector device 106, the width will correspond to that ofthe associated side of the insulation element 102 and, accordingly, isabout 5 mm to 16 mm. The end portions 150 and 152 extend about 15 cm to60 cm from the longitudinal ends of the insulation element 102. Thefluid slot 112 will typically be about 1 to 3 mm wide. As a result,there will be relatively wide (e.g. about 2 mm to 9.5 mm) insulationelement portions on either side of the fluid slot 112 that will insulatethe tissue associated therewith from levels of coagulation energy thatare great enough to coagulate tissue during the creation of a typicallesion (i.e. about 50 to 180 seconds). In the context of a pulmonaryvein isolation procedure such as that described above with reference toFIGS. 8 and 9, it is desirable to have about 5-10 mm between the lesionand the pulmonary veins in order to minimize stenosis risk.

Another exemplary positioning wrap is generally represented by referencenumeral 100 a in FIGS. 10-12A. The positioning wrap 100 a issubstantially similar to the positioning wrap 100 described above withreference to FIGS. 1-3 and 5-8 and similar elements are represented bysimilar reference numerals. With respect to the differences, theinsulation element 102 a has an overall tapered shape in cross-sectionand a smooth probe lumen 108 a. The tapered shape of the insulationelement 102 a keeps the wrap 100 a from buckling, keeps the slot 112open, and gives maximum contact along the length of slot. The thin edgesprovide flexibility. The insulation element 102 a is also configuredsuch that it has a closed end 156. As such, a probe (such as theexemplary probe 230 without the pull wire 238 and the electrodes 204closer to the distal end) will simply be fed into the positioning wrap100 a until it reaches the closed end 156. This arrangement eliminatesthe need for a fluidic seal (e.g. the seal 116) at that end of theinsulation element 102 a. The exemplary insulation element 102 a alsolacks a fluidic seal at the other end. Instead, the positioning wrap 100a is provided with a hemostasis valve 158 that includes a seal 160 (FIG.12A). The hemostasis valve 158 is connected to a tube 162, which extendsinto the probe lumen 108 a by way of an aperture 164, and to a tube 166,which extends to the stopcock 140.

The positioning wrap 100 a operated in substantially the same way as thepositioning wrap 100. For example, the positioning wrap 100 a may bepositioned in the manner illustrated in FIG. 8 with or without theelectrode supporting probe already in place within the probe lumen 108a. In those instances where the probe is not within the positioning wrap100 a prior to positioning, the probe may be fed into the wrap after itis positioned. Thereafter, conductive fluid may be infused (orventilated) through the hemostasis valve 158/tube 162, and ventilated(or infused) through the tubes 128 and 130. Tissue coagulation energy isthen transmitted from the power supply and control apparatus to one,some or all of the electrodes on the probe to form a lesion.

Still another exemplary positioning wrap is generally represented byreference numeral 100 b in FIGS. 13-15. The positioning wrap 100 b issubstantially similar to the positioning wraps 100 and 100 a describedabove with reference to FIGS. 1-3, 5-8 and 10-12A and similar elementsare represented by similar reference numerals. With respect to thedifferences, the insulation element 102 b has an overall shape that issimilar to the insulation element 100, but lacks the fluid lumens 120and 122. The fluid lumens 120 and 122 are unnecessary in the positioningwrap 100 b because the conductive fluid is not being infused andventilated from the same end of the wrap. The conductive fluid insteadflows in one end of the probe lumen 108 b and out the other. To thatend, the positioning wrap 100 b is provided with a pair of hemostasisvalves 158 and 168. As noted above, the hemostasis valve 158 isconnected to tubes 162 and 166. Tube 162 extends into the probe lumen108 b, while tube 166 extends to the stopcock 140. The hemostasis valve168, which is identical to valve 158 includes a seal (not shown), and isconnected to a tube 170 that extends into the probe lumen 108 b by wayof an aperture 172. The hemostasis valve 168 is also connected to thestopcock 142 by a tube 174.

The positioning wrap 100 b operated in substantially the same way as thepositioning wrap 100. For example, the positioning wrap 100 b may bepositioned in the manner illustrated in FIG. 8 with or without theelectrode supporting probe already in place within the probe lumen 108b. In those instances where the probe is not within the positioning wrap100 b prior to positioning, the probe 230 may be pulled through the wrapwith the pull wire 238 (note FIG. 15) after the wrap is positioned.Thereafter, conductive fluid may be infused (or ventilated) through thehemostasis valve 158/tube 162, and ventilated (or infused) through thehemostasis valve 168/tube 172. Tissue coagulation energy is thentransmitted from the power supply and control apparatus to one, some orall of the electrodes 234 on the probe 230 to form a lesion.

The exemplary positioning wrap 100 c illustrated in FIGS. 16-18 issubstantially similar to the positioning wraps 100 and 100 a describedabove with reference to FIGS. 1-3, 5-8 and 10-12A and similar elementsare represented by similar reference numerals. The overallcross-sectional shape of the insulation element 102 c is, for example,similar to that of the insulation element 102. The positioning wrap 100c also employs a hemostasis valve 158 and has a closed end, as does thepositioning wrap 100 a. With respect to the primary differences, thepositioning wrap 100 c includes suction capability and tissuestimulation and/or sensing capabilities. The suction capability may beused to fix the position of the positioning wrap 100 c relative to thetarget tissue. Tissue stimulation and sensing may be used to confirmwhether or not a therapeutic lesion has been formed by, for example,supplying tissue stimulation energy on one side of a lesion and/ormonitoring tissue (either electrically or visually) on the other side ofthe lesion. Tissue stimulation may also be used to determine lesiondepth and, correspondingly, whether or not a lesion is transmural. Theenergy transmission element 104 c is also slightly different than theenergy transmission element 104 in that the energy transmission element104 c is relatively narrow (i.e. slightly wider than the fluid slot 112)so that it does not interfere with the suction and tissue stimulationand/or sensing.

With respect to suction, the positioning wrap 100 c includes a pluralityof suction ports 176 on opposite sides of the energy transmissionelement 104 c. A pair of internal suction lines 178 are formed in theinsulation element 102 c and each of the suction ports 176 is connectedto a suction line by a suction aperture 180. The suction lines 178 arealso connected to a connector 182 such as, for example, the illustratedLuer connector. A suction source 340 (FIG. 16) may be connected to theconnector 182 by a flexible tube 342. When the suction source 340 isactuated, the suction ports 176 will fix the position of the positioningwrap 100 c relative to the target tissue.

A plurality of fluid apertures (not shown), which are connected to theprobe lumen 108 or to the fluid lumens 120/122, may be provided betweenthe slot 112 and the suction ports 176. These fluid apertures may beused to weep fluid that hydrates the tissue and prevents desiccation,and also improves RF coupling, suction seal and temperature sensing.

Turning to tissue stimulation and sensing, the positioning wrap 100 cincludes tissue stimulation electrodes 184 and, in some instances,sensing electrodes 186. In the exemplary implementation, the stimulationand sensing electrodes 184 and 186 are located adjacent to the suctionports 176 on opposite sides of the fluid slot 112 and the energytransmission element 104 c. As such, the tissue stimulation and sensingelectrodes 184 and 186 will be on opposite sides of the lesion formed bythe energy passing through the energy transmission element 104 c. Theelectrodes 184 and 186, which are held firmly against tissue when thesuction source 340 is activated, are relatively small, e.g. 0.5 mm to 1mm in diameter and about 0.01 mm thick. Although not required, thestimulation and sensing electrodes 184 and 186 are also arranged inbipolar pairs in the exemplary implementation. Other electrodearrangements include, but are not limited to, arrangements with greateror fewer numbers of bipolar pairs and unipolar arrangements where asingle electrode is positioned adjacent to each of the suction ports176.

The tissue stimulation and sensing electrodes 184 and 186 may be formedby coating a conductive material onto the insulation element 102 c usingconventional coating techniques or an IBAD process. Suitable conductivematerials include platinum-iridium and gold. An undercoating of nickel,silver or titanium may be applied to improve adherence. Conductive inkcompounds, such as silver-based flexible adhesive conductive ink(polyurethane binder) or metal-based adhesive conductive inks (e.g.platinum, gold, or copper based) may also be pad printed onto theinsulation element 102 c.

Respective sets of signal lines (not shown) extend from the stimulationand sensing electrodes 184 and 186, through the signal line lumens 188and 190 to a cable 192. The cable 192 is connected to an EP recordingapparatus 350 and the EP recording apparatus is connected to, anddirects the tissue stimulation and recording associated with, a tissuestimulation apparatus 360 (FIG. 16). A suitable EP recording apparatus350 is the Prucka CardioLab 7000® from GE Medical Systems. One exemplarytype of tissue stimulation apparatus 360 is a conventional pacingapparatus, such as the Medtronic Model Nos. 5330 and 5388 external pulsegenerators. The power delivered to tissue for stimulation purposes willtypically be significantly less than that which would form a transmuralor otherwise therapeutic lesion in tissue. An exemplary stimulationenergy delivery would consist of two stimulation pulses per second, eachpulse being 1 millisecond. The maximum amplitude would be 10 mA, whichwould create 5 V, for a total power delivery of 100 μW, as compared tothe 5 to 150 W required to coagulate tissue.

With respect to lesion formation, the positioning wrap 100 c operated ina similar manner to the positioning wrap 100 a. For example, thepositioning wrap 100 c may be positioned in the manner illustrated inFIG. 8 with or without the electrode supporting probe already in placewithin the probe lumen 108 a. The suction source 340 may then beactuated in order to insure that the positioning wrap 100 c does notmove and that there is good contact between the energy transmissionelement 104 c and electrodes 184/186 and the tissue. In those instanceswhere the probe is not within the positioning wrap 100 c prior topositioning, the probe may be fed into the wrap after it is positioned.Conductive fluid may be infused (or ventilated) through the hemostasisvalve 158/tube 162, and ventilated (or infused) through the tubes 128and 130. Tissue coagulation energy is then transmitted from the powersupply and control apparatus to one, some or all of the electrodes onthe probe to form a lesion.

The stimulation and sensing electrodes 184 and 186 may then be used todetermine whether or not a therapeutic lesion has been properly formed.For example, after the positioning wrap 100 c has been used in themanner discussed above with reference to FIGS. 8 and 9 to form apulmonary vein isolating lesion, one of the pairs of stimulationelectrodes 184 may be used to supply a bipolar pacing pulse on the sideof the lesion opposite the left atrium. The physician can determinewhether or not a therapeutic lesion (or “complete block”) has beenformed by observing the left atrium. If the pacing pulse is able tocross the lesion, the heart will beat faster (e.g. 120 beats/minute).This may be determined by observation or by use of an ECG machine thatis monitoring the heart. Here, additional coagulation will be requiredto complete the lesion. The failure to stimulate the heart from the sideof the lesion opposite the left atrium is, on the other hand, indicativeof the formation of a therapeutic lesion. Nevertheless, because musclebundles are not always connected near the pulmonary veins, it ispreferable that the stimulation energy be applied to a number of tissueareas, from a number of stimulation electrode pairs, on the side of thelesion opposite the left atrium to reduce the possibility of falsenegatives. The sensing electrodes 186, which are located on the oppositeside of the lesion, may also be used to capture the stimulus from thepacing electrodes 184.

Alternatively, the sensing electrodes 186 may be used to monitor tissuewithin the region that was intended to be isolated. In the context ofpulmonary vein isolation, for example, the sensing electrodes 186 may beplaced in contact with viable tissue on the pulmonary vein side of thelesion. Local activation within the isolated region from the heart'snatural stimulation is indicative of a gap in the lesion.

Additional details concerning tissue stimulation and sensing areprovided in U.S. application Ser. No. 10/727,143, which is entitled“Surgical Methods And Apparatus For Forming Lesions In Tissue AndConfirming Whether A Therapeutic Lesion Has Been Formed,” and isincorporated herein by reference.

As noted above with reference to FIGS. 6 and 7, the inner surface of theprobe lumen 108 in the exemplary positioning wrap 100 includes aplurality of square protrusions 144 and crisscrossing channels 146. Thepresent inventions are not limited to such configurations and a varietyof other configurations may be employed. By way of example, and notlimitation, and referring first to FIGS. 19A and 19B, the exemplaryinsulation element 102 d includes a plurality of ring shaped protrusions144 d extending inwardly from the surface of the probe lumen 108 d. Theprobe lumen 108 e in the exemplary insulation element 102 e illustratedin FIGS. 19C and 19D includes a plurality of longitudinally extendingprotrusions 144 e and channels 146 e. Turning to FIGS. 19E and 19F, theinsulation element 102 f includes a probe lumen 108 f with a pluralityof semi-spherical protrusions 144 f and a channel 146 f that extendsbetween the protrusions. The probe lumen 108 g in the insulation element102 g includes a helical protrusion 144 g and a helical channel 146 g.The protrusions 144 d-g should be sized such that there is a small gapbetween the protrusions and the probe (which is shown in dashed lines inFIGS. 19B, 19D, 19F and 19H.

Another exemplary insulation element is generally represented byreference numeral 102 h in FIG. 19I. The insulation element 102 hincludes a plurality of reinforcing members 194, such as straight orpre-shaped polymer, composite or metal members, that prevent twisting ofthe positioning wrap, hold a shaped positioning wrap straight forintroduction, or provide lumens (not shown) for temperature sensor wiresor other elements. Although the probe lumen 108 h is smooth, it may beconfigured in any of the other manners described above.

Insulation elements may also perform functions in addition to insulationand fluid transmission. As illustrated for example in FIGS. 20-22, theinsulation element 102 i in a positioning wrap 100 i includes a pair ofpre-shaped reinforcing members 196 (e.g. thin strips of Nitinol) with apre-shaped loop configuration and a removable stylet 198 (e.g. a steelrod) that is straight and rigid enough to overcome the bending forcesapplied by pre-shaped reinforcing members 196. The removable stylet 198is carried within a tube 200 that defines a longitudinally extendinglumen within the insulation element 102 i. Absent the presence of thestraightening force applied by the removable stylet 198, the insulationelement 102 i, with its pre-shaped reinforcing members 196, will bendthe positioning wrap 100 i into the loop illustrated in FIG. 22 and willmaintain the loop during lesion formation procedures. Additionally,although the probe lumen 108 i is smooth, it may be configured in any ofthe other manners described above.

In the illustrated embodiment, the longitudinal ends of the energytransmission element 104 overlap slightly in order to insure that thelesion formed thereby will be a complete circle. Alternatively,pre-shaped reinforcing members 198 may be configured such that thelongitudinal ends abut one another, or such that there is a gap betweenthe longitudinal ends, if the intended application so requires.Additionally, although the illustrated reinforcing member has asubstantially circular shape, any shape suitable for the intendedapplication (e.g. a U-shape) may be employed. A pre-shaped reinforcingmember(s) and stylet arrangement may be incorporated into any of thepositioning wraps described herein with reference to FIGS. 1-19 h.Moreover, pre-shaping may also be accomplished without the use ofreinforcing members by, for example, molding the insulation element intothe desired shape.

During use, the removable stylet 198 will be in place within the tube200 prior to deployment of the positioning wrap 100 i. The removablestylet 198 will be withdrawn in the direction of arrow A (FIG. 20) asthe wrap is advanced in a direction tangential to the target tissuestructure, thereby allowing the pre-shaped reinforcing members 196 tobend the wrap into a loop shape around the target structure. The stylet198 is preferably slightly longer than the insulation element 102 i inorder to provide a free end that may be grasped by the physician. Thestylet 198 may, in some instances, have a slight curvature whereapplications so require.

In addition to bending the positioning wrap 100 i into the bentorientation illustrated in FIG. 22, the pre-shaped reinforcing members196 will maintain the positioning wrap in the bent orientation duringlesion formation procedures. As such, the connector device 106 need notbe used (although it may be used if desired) to maintain the positioningwrap in the loop orientation. The end portions 150 and 152 may still beused, however, to pull the positioning wrap around a tissue structure asit is being positioned for a procedure.

As illustrated above, the configuration of the insulation element issusceptible to a wide degree of variation. There are also a number ofalternative connector configurations. Turning to FIGS. 23-26, theexemplary positioning wrap 100 j is substantially similar to thepositioning wrap 100 described above with reference to FIGS. 1-9 andsimilar elements are represented by similar reference numerals. Here,however, the positioning wrap 100 j includes a fastener 202 that may beused instead of, or in addition to, the connector device 106 when fixingthe position of the wrap around an organ.

The fastener 202 includes a pair of fastening elements 204 and 206 thatare associated with the longitudinal ends of the insulation element 102.The exemplary fastening elements 204 and 206 are hook and loop fastenerstrips, such as Velcro® strips. Fastening element 204 is carried on thebottom of the connector device main portion 148 and faces downwardly (inthe orientation illustrated in FIG. 23), while the fastening element 206is carried by a support 208 that is secured to the connector device mainportion and faces upwardly. So arranged, the fastening elements 204 and206 will face one another, thereby allowing them to be connected to oneanother, when the positioning wrap 100 j is bent into a loop in themanner illustrated in FIG. 26.

The exemplary fastener 202 may also be used in combination with thepositioning wraps described above with reference to FIGS. 10-22.

Other exemplary fastening elements include devices that will hold theconnector device end portions 150 and 152, such as clamps andspring-biased locks. In those instances where the end portions 150 and152 include knots, cleats (i.e. a tube with slots that receive theknots) may be employed.

Another exemplary positioning wrap is generally represented by referencenumeral 100 k in FIGS. 27 and 28. The positioning wrap 100 k issubstantially similar to the positioning wrap 100 described above withreference to FIGS. 1-9 and similar elements are represented by similarreference numerals. Here, however, the connector device 106 k includes apair of flexible pull strings 210 and 212 and a pair of flexible endstrings 214 and 216. The pull strings 210 and 212 are secured to theinsulation element 102, and preferably along the entire length of theinsulation element, with adhesive 218. The longitudinal ends of the pullstrings 210 and 212 are secured to one another, and to the end strings214 and 216, by knots 220 (or other fastening methods). The connectordevice 106 k may also be used in place of the connector device 106 inthe positioning wraps described above with reference to FIGS. 10-26.

The exemplary positioning wraps illustrated in FIGS. 1-3 and 5-28 mayalso be configured in a manner that will help the physician distinguishvarious elements from one another. For example, the positioning wrap 100l illustrated in FIG. 29, which is essentially identical to the wrap 100described above with reference to FIGS. 1-9, includes a connector device106 l that is relatively dark in color, while the insulation element 102is relatively light in color. This may also be reversed, with theinsulation element 102 formed from a relatively dark material and theconnector device 106 l formed from a relatively light material. Thecolor of the insulation element 102 may also be selected so as to helpthe physician identify various apparatus elements during surgicalprocedures. Stripes and other patterns may also be employed. A visiblescale may also be provided on the insulation element or the connectordevice in order to allow the physician to monitor and manage the fulllength of the apparatus during the procedure.

The exemplary lesion formation apparatus described above with referenceto FIGS. 1-29 may also be provided with a movable insulation device thatprevents some of the tissue that would otherwise be ablated by thecoagulation energy from being ablated. As illustrated for example inFIG. 30, a slidable insulation sleeve 222 is positioned around a portionof the positioning wrap 100. The length of the insulation sleeve 222will vary from application to application, but will typically be longerthat the insulation element 102 itself and up to twice the length of theinsulation element. This allows the insulation sleeve 222 to provide anelectrically insulative barrier between the energy transmission element104 and the patient, from the exterior of the body to the target tissueregion. Suitable materials for the insulation sleeve include silicone,polyurethane, thin film Kapton®, PTFE impregnated fabric and polyester.The insulation sleeve 222 may, for example, be used to cover themajority of the energy transmission element 104 during touch upprocedures to fill in gaps in lesions. Here, the insulation sleeve 222may be pulled proximally until the desired length of the energytransmission element 104 is exposed.

In an alternative configuration, which is illustrated in FIGS. 31 and32, the exemplary insulation sleeve 224 includes a window 226 thatallows small lesions to be formed in specific locations. Sleeve 224 isalso configured to prevent the positioning wrap 100 from rotating and toinsure that the energy transmission element 104 is aligned with thewindow 226. More specifically, the surface 228 of the insulation sleeveinternal lumen is shaped in a manner substantially similar to theinsulation element 102.

Temperature sensors may also be provided on the positioning wrapsdescribed above with reference to FIGS. 1-29. For example, thepositioning wrap 100 m illustrated in FIGS. 32A and 32B, which isessentially identical to the wrap 100, includes a plurality oftemperature sensors 227 between the insulation element 102 m and thenarrower energy transmission element 104 c. The temperature sensors 227are located on each side of the fluid slot 112, preferably relativelyclose (e.g. within 0.5 to 1.5 mm) to the slot. Suitable temperaturesensors include, but are not limited to, thermocouples and thermistors.The insulation element 102 m also includes a pair of lumens 229 for thesignal wires (not shown) that extend over the top of energy transmissionelement 104 c and are respectively connected to the temperature sensors227. The signal wires are associated with a cable and connector (notshown) arrangement that extends from one end of the positioning wrap 100m and may be connected to the power supply and control device that issupplying energy to the probe being used in combination with the wrap.

In the exemplary positioning wraps described above with reference toFIGS. 1-29, the fluid slots 112 are located along the centerline of theinsulation element and, accordingly, the width of the insulated regionson either side of the fluid slots are equal. It should be noted,however, that this is not required and the above-described positioningwraps may be reconfigured if applications so require such that there isa wider insulated area on one side of the fluid slot 112 than the other.

III. Exemplary Clamp Based Lesion Formation Apparatus

As illustrated for example in FIG. 33, an exemplary surgical system 20in accordance with one embodiment of a present invention includes thefluid supply and control apparatus 300, the power supply and controlapparatus 320, and an electrophysiology clamp apparatus 400. The clampapparatus 400 includes a clamp and a tissue coagulation assembly thatmay be secured to the clamp. As used herein, the term “clamp” includes,but is not limited to, clamps, clips, forceps, hemostats, and any othersurgical device that includes a pair of opposable clamp members thathold tissue, at least one of which is movable relative to the other. Insome instances, the clamp members are connected to a scissors-likearrangement including a pair of handle supporting arms that arepivotably connected to one another. The clamp members are secured to oneend of the arms and the handles are secured to the other end. Certainclamps that are particularly useful in minimally invasive proceduresalso include a pair of handles and a pair of clamp members. Here,however, the clamp members and handles are not mounted on the oppositeends of the same arm. Instead, the handles are carried by one end of anelongate housing and the clamp members are carried by the other. Asuitable mechanical linkage located within the housing causes the clampmembers to move relative to one another in response to movement of thehandles. The clamp members may be linear or have a predefined curvaturethat is optimized for a particular surgical procedure or portionthereof. The clamp members may also be rigid or malleable.

One example of a clamp that may be employed in the electrophysiologyclamp apparatus 400 is generally represented by reference numeral 402 inFIGS. 33-36. Referring more specifically to FIGS. 34-36, the clamp 402includes a pair of rigid arms 404 and 406 that are pivotably connectedto one another by a pin 408. The proximal ends of the arms 404 and 406are respectively connected to a pair handle members 410 and 412, whilethe distal ends are respectively connected to a pair of clamp members414 and 416. The clamp members 414 and 416 may be rigid or malleableand, if rigid, may be linear or have a pre-shaped curvature. A lockingdevice 418 locks the clamp in the closed orientation, and prevents theclamp members 414 and 416 from coming any closer to one another than isillustrated in FIG. 34, thereby defining a predetermined spacing betweenthe clamp members. The clamp 402 is also configured for use with a pairof soft, deformable inserts (not shown) that may be removably carried bythe clamp members 414 and 416 and allow the clamp to firmly grip abodily structure without damaging the structure. To that end, the clampmembers 414 and 416 each include a slot 420 (FIGS. 35 and 36) that isprovided with a sloped inlet area 422 and the inserts include matingstructures that are removably friction fit within the slots. Theexemplary tissue coagulation assembly 424 (FIG. 33 and 37) may bemounted on the clamp members in place of the inserts.

As illustrated in FIG. 37, the exemplary tissue coagulation assembly 424includes a tissue coagulation device 426 that may be connected to one ofthe clamp members and a temperature sensor device 428 that may beconnected to the other. The tissue coagulation device 426 andtemperature sensor device 428 are respectively carried on supportstructures 430 and 432, which are connected to a tubular member 434 by aconnector 436. The tubular member 434 is secured to a handle 438.

As illustrated for example in FIGS. 38-43, the exemplary tissuecoagulation device 426 includes an insulation element 440, an energytransmission element 442 and a mounting device 444 that may be used tomount the tissue coagulation device on the clamp 402. A lumen 446extends through the insulation element 440 and a plurality of electrodes448 (or other energy emission elements) are carried on the portion ofthe support structure 430 that is located within the lumen. Tissuecoagulation energy from the electrodes 448 is transferred to, andthrough, the energy transmission element 442 by electrically conductivefluid. To that end, the inner diameter of the lumen 446 is slightlygreater than the outer diameter of the support structure 430 and a fluidtransmission space 450 is defined between the support structure and theinner surface of the lumen 446. The insulation element 440 also includesa fluid slot 452 that extends from the fluid transmission space 450 tothe energy transmission element 442. The longitudinal ends of the fluidtransmission space are sealed by adhesive material 454, which is alsoused to secure the tissue coagulation device 426 to the supportstructure 430.

Referring to FIGS. 37-43, tissue coagulating energy and conductive fluidis supplied to the exemplary tissue coagulation device 426 by way of thesupport structure 430. To that end, the support structure 430 includes awire lumen 456, a fluid infusion lumen 458, and a fluid ventilationlumen 460. The distal ends of the lumens 456-460 are sealed by a plug461. Fluid from the infusion lumen 458 enters the fluid transmissionspace 450 by way of an infusion aperture 458 a (FIG. 39) and is entersthe ventilation lumen 460 by way of a ventilation aperture 460a (FIG.40). The tubular member 434 includes a wire lumen 462, a fluid infusionlumen 464, and a fluid ventilation lumen 466 that are connected to thecorresponding lumens in the support structure 430 by the connector 436.Power wires 468 extend from the electrodes 448, and through the wirelumens 456 and 462, to a connector (such as a PC board) in a slot 470formed in the handle 438 (FIG. 37). The connector (and electrodes 448)may be connected to the ESU 322 by way of the cable 324 and theconnector 326 that may be received by the slot 470. The infusion andventilation lumens 464 and 466 are connected to the tubes 465 and 467within the handle 438, which are in turn connected to the tubes 308 and310 from the fluid supply and control apparatus 300 by way of theillustrated stopcocks or other suitable devices.

The exemplary temperature sensor device 428 illustrated in FIGS. 33, 37,44 and 45 includes a plurality of temperature sensors 472 that arecarried on the support structure 432 and a mounting device 474 that maybe used to mount the temperature sensor device on the clamp 402. Thetemperature sensors 472 (e.g. thermocouples or thermistors) areconnected to signal wires 476 that extend through a lumen 477 in thesupport structure 432 and the wire lumen 462 in the tubular member 432.The signal wires 476 are also connected to the connector in the handleslot 470.

Turning to the manner in which the tissue coagulation device 426 issecured to the clamp 402, and referring to FIGS. 35, 36 and 38-41, themounting device 444 includes a cup-shaped main portion 478 that isconfigured to receive the insulation element 440, and a connector 480that is configured to removably mate with the slot 420 in the clamp 402.Adhesive may be used to secure the insulation element 440 within themain portion 478. The cup-shaped main portion 478 is substantially rigidand covers the substantial majority of the bottom and sides (when viewedin the orientation illustrated in FIGS. 39-41) of the insulation element440. As a result, the main portion 478 prevents undesired deformation ofthe insulation element 440 during tissue coagulation procedures. Theexemplary connector 480 is provided with a relatively thin portion 482and a relatively wide portion 484, which may consist of a plurality ofspaced members (as shown in FIG. 38) or an elongate unitary structure,in order to correspond to the shape of the slot 420 in the clamp 402.

With respect to the manner in which the temperature sensor device 428 issecured to the clamp 402, and referring to FIGS. 35, 36 and 45, themounting device 474 includes a main portion 486 with a groove 488 thatis configured to receive the support structure 432, and a connector 480that mates with the clamp slot 420. The configuration of the groove 488allows the support structure 432 to be snap fit into the main portion486. Adhesive may also be used within the groove 488 to insure that thesupport structure 432 does not separate from the connector device 474.

Although the configuration of the tissue coagulation assembly 424 mayvary from application to application to suit particular situations, theexemplary tissue coagulation assembly 424 is configured such that theenergy transmission element 442 and the temperature sensors 472 will beparallel to one another as well as relatively close to one another (i.e.a spacing of about 1-10 mm) when the clamp 402 is in the closedorientation. Such an arrangement will allow the tissue coagulationassembly to firmly grip a bodily structure without cutting through thestructure.

With respect to dimensions, the exemplary insulation element 440 isabout 7 mm to 20 mm wide, along the surface that supports the energytransmission element 442, and about 4 mm to 20 mm thick. The fluid slot452 will typically be about 1 to 3 mm wide. As a result, there will be arelatively wide insulation element portions (e.g. about 4 mm to 19 mm)on either side of the fluid slot 452 that will insulate the tissueassociated therewith from levels of coagulation energy that are greatenough to coagulate tissue during a typical lesion formation procedure(i.e. about 50 to 180 seconds). The length of the exemplary insulationelement 440 is about 25 to 70 mm. Suitable materials for the insulationelement 440 include the same materials that are used to form theinsulation element 102 because the mounting device 444 is sufficientlyrigid to provide a stable structure. With respect to the energytransmission element 442, the materials are the same as those discussedabove with respect to the energy transmission element 104.

Turning to the materials used to form other aspects of the tissuecoagulation assembly 424, the support structures 430 and 432 and tubularmember 434 may be formed from PET or polyurethane tubing. The mountingdevices 444 and 474 may be formed from polyurethane, nylon, Pebax®,ceramics, PES, PEEK, or metals such as aluminum, copper, stainless steeland Nitinol.

The exemplary clamp apparatus 400 may be reconfigured in a variety ofways. By way of example, but not limitation, one alternative tissuecoagulation assembly includes a pair of the tissue coagulation device426 with one carried on each of the clamp members 414 and 416. Here,temperature sensors may be provided on one or both of the tissuecoagulation devices 426 in the manner described above with reference toFIGS. 32A and 32B. Additionally, the insulation element 440 and themounting device 444 may be combined into an integrally formed, one-piecestructure.

The exemplary clamp apparatus 400 may be used to form lesions in thefollowing manner. The clamp members 414 and 416 may be positioned suchthat the tissue coagulation device 426 and temperature sensor device 428are on opposite sides of a tissue structure. For example, the tissuecoagulation device 426 and temperature sensor device 428 may bepositioned on opposite sides of a single pulmonary vein or a pair ofpulmonary veins. The clamp members 414 and 416 may then be brought intoa completely closed orientation or, depending on the tissue structure, aslightly open orientation so long as the tissue structure is firmlyheld. After the fluid transmission space 450 and fluid slot 452 arefilled with conductive fluid from the fluid supply and control apparatus300, the power supply and control apparatus 320 may be used to supplycoagulation energy to the electrodes 448. The temperature sensors 472monitor the tissue temperature on the side of the target tissuestructure opposite the energy transmission element 442.

The inventor herein has determined that temperature on the side of thetarget tissue structure opposite the energy transmission element 442 isindicative of lesion transmurality (i.e. whether or not a lesion thatextends from one side of the target tissue structure to the other hasbeen formed). More specifically, the inventor herein has determined thatmeasured temperatures of about 50° C. to about 60° C. on the side of thetissue structure opposite the side that is in contact with the energytransmission element 442 for at least 1 second are indicative of theformation of a transmural lesion. The power supply and control apparatus320 may, therefore, be configured to discontinue energy transmissionwhen a predetermined temperature (e.g. a temperature between about 50°C. and about 60° C.) is measured by the temperature sensors 472 for atleast 3 seconds. Alternatively, or in addition, the power supply andcontrol apparatus 320 may also be configured to provide an audible orvisible indication that the predetermined temperature has been measured.

IV. Exemplary Probe Based Lesion Formation Apparatus

As illustrated for example in FIG. 46, an exemplary surgical system 30in accordance with one embodiment of a present invention includes thefluid supply and control apparatus 300, the power supply and controlapparatus 320, a surgical probe 500 having a shaft 502, a handle 504,and a plurality of electrodes 506, and an insulation element 600 thatprotects non-target tissue from unintended contact with the electrodes506.

Turning first to the insulation element, the exemplary insulationelement 600 illustrated in FIGS. 46-49 includes a main body 602 and aslot 604. The slot 604 is configured to receive the probe shaft 502, byway of an opening 606, and to removably secure the insulation element tothe probe shaft. In other words, although the level of force requiredfor removal of the insulation element 600 from the probe shaft 502 willbe greater than that which will be experienced during a typical tissuecoagulation procedure, it will be readily removable by the physician.The configuration of a slot 604 will, of course, depend on theconfiguration of the surgical probe with which it is intended to beused. The illustrated probe shaft 502 and electrodes 506 are generallycylindrical in shape and the slot 604 has a corresponding arcuatecross-sectional shape. The arc is preferably greater than 180 degrees sothat the main body 602 will deflect when the probe shaft 502 is insertedinto the slot 604 through the opening 606 and then snap back to hold theinsulation element 600 in place.

The insulation element 600 also makes the surgical probe 500 “onedirectional” in that energy will only be transferred through the opening606. Such an arrangement is more efficient that one in which the energytransfer can take place along the entire perimeter of the electrodes506.

As illustrated for example in FIGS. 47 and 48, the exemplary insulationelement 600 also includes side walls 608 that slant away from theopening 608. An insulation element with such a cross-section will bebetter able to flex when bent, especially when bent in a full orsemi-circle.

With respect to materials, suitable materials for the insulation element600 include flexible polymer (elastomer) open and closed cell foams. Inthose instance where open cell foams are used, the base member mayinclude a sealing skin (not shown) to prevent fluid absorption. Flexiblethermoplastics and thermoset polymers may also be employed. Materialsthat have a hardness rating of 25 to 35 (Shore A) are preferred.

The overall dimensions of the insulation element 600 will depend uponthe surgical probe with which it is intended to be used. In theexemplary implementation, the length of the insulation element 600 isslightly longer that the distance between the proximal end of theproximal-most electrode 506 and the distal end of distal-most electrode,i.e. about 15 to 30 cm. The overall width of the insulation element 600is about 7 to 20 mm, while the width of the opening is preferably 606 isabout 1 to 3 mm. The aspect ratio, i.e. the width to thickness (orheight) ratio, is about 2-3 to 1 and, accordingly, the thickness of theexemplary insulation element 600 is about 3 to 10 mm.

In alternative configurations, adhesive may be used to permanentlysecure the insulation element 600 to the surgical probe 500, especiallyin those instances where the arc of the slot 604 is less than 180degrees. Adhesive may be used for this purpose.

Insulation elements in accordance with the present inventions may alsobe linear prior to the bending of the shaft on which they are mounted(as illustrated in FIGS. 46-49) or pre-shaped. Pre-shaping may beaccomplished by molding the insulation element with a particular shape.The pre-shaping may also be accomplished by added pre-shaped elements,such as the plurality of polymer, composite or metal members reinforcingmembers 194 illustrated in FIG. 19I or the pre-shaped reinforcingmembers 196 (with or without the removable stylet 198) illustrated inFIGS. 20-22.

Turning to the exemplary surgical probe 500, and referring to FIGS. 46and 50-52, the shaft 502 is relatively short (e.g. about 3 cm to about12 cm in length) and relatively stiff. In other words, the shaft isrigid, malleable, or somewhat flexible. A rigid shaft cannot be bent. Amalleable shaft is a shaft that can be readily bent by the physician toa desired shape, without springing back when released, so that it willremain in that shape during the surgical procedure. Thus, the stiffnessof a malleable shaft must be low enough to allow the shaft to be bent,but high enough to resist bending when the forces associated with asurgical procedure are applied to the shaft. A somewhat flexible shaftwill bend and spring back when released. However, the force required tobend the shaft must be substantial.

In the illustrated embodiment, the shaft 502 consists of a proximalportion 508, including a malleable hypotube 510 and an outer polymercoating 512, and distal portion 514, including a malleable mandrel 516and a multi-lumen electrically non-conductive outer structure 518. Theproximal portion 508 will typically be about 3 to 30 cm in length, whilethe distal portion will typically be about 10 to 60 cm in length. Theproximal end of the malleable mandrel 516 is secured to the innersurface of the distal end of the hypotube 510 and the distal end of themalleable mandrel is secured to a tip member 520. The exemplary tipmember 520 is provided with a suture aperture 521 (FIG. 50). If desired,physicians may pass a suture through the aperture 521 and use the sutureto pull the shaft 502 around a body structure.

The exemplary surgical probe 500 is a fluid cooled surgical probe and,as illustrated in FIGS. 51 and 52, the electrically non-conductive outerstructure 518 includes fluid inlet and outlet lumens 522 and 524, powerand signal wire lumens 526 and 528, a central lumen 530 for the mandrel516. To that end, the tip member 520 includes a connection lumen (notshown) that connects the inlet lumen 522 to the outlet lumen 524, aswell as a pair of plugs (not shown) to seal the power and signal wirelumens 526 and 528. Heat from the electrodes 506 is transferred throughthe outer structure 518 to fluid that is flowing through the inlet andoutlet lumens 522 and 524. Accordingly, in addition to beingelectrically non-conductive, the material used to form the outerstructure 518 should be relatively high in thermal conductivity. As usedherein, “relatively high” thermal conductivity is at least about 1 W/m·Kand preferably ranges from about 1 to about 10 W/m·K. Suitableelectrically non-conductive, thermally conductive thermoplastics for theouter structure 518 include flexible thermoplastic polymer materials,such as nylon or polyurethane, which are filled with a filler thatpromotes heat transfer. Suitable fillers include graphite, aluminum,tungsten and ceramic powders. Another suitable filler is CarborundumCarboTherm™ boron nitride powder manufactured by Saint-Gobain inCavaillon, France.

In addition to the aforementioned fillers, heat transfer may be promotedby minimizing the thickness of the electrically non-conductive materialbetween the lumens 522 and 524 and the electrodes 506 and by maximizingthe cross-sectional area of the inlet and outlet lumens. With respect tothe outer structure 518 illustrated in FIG. 52, for example, in animplementation where the outer diameter of the outer structure is about8 French (2.66 mm), the thickness of the outer wall 532 between theelectrodes 506 and the inlet and outlet lumens 522 and 524 will be about0.08 mm to about 0.36 mm. It should be noted that when the outer wallthickness is about 0.02 mm or less, materials with less than “relativelyhigh” thermal conductivities, such as Pebax® material and polyurethane,may also be used for the outer structure 518.

As illustrated for example in FIG. 46, fluid may be supplied to thesurgical probe 500 by way of an infusion tube 534, which is connected tothe inlet lumen 522. The infusion tube 534 extends through an aperturein the handle 504 and is provided with stop-cock, which may be connectedto the tube 308 that is associated with the fluid supply and controlapparatus outlet port 304. Similarly, a ventilation tube 536 isconnected to the outlet lumen 524 and extends through an aperture in thehandle 504. The ventilation tube 536 may be connected to the tube 310that is associated with the inlet port 306 on the fluid supply andcontrol apparatus 300.

The cooling fluid is not limited to any particular fluid. Preferably,however, the fluid will be a low or electrically non-conductive fluidsuch as sterile water or 0.9% saline solution in those instances wherethe fluid will not be used to transmit current to tissue. A suitablefluid inlet temperature is about 0 to 25° C. and the fluid supply andcontrol apparatus 300 may be provided with a suitable cooling system, ifdesired, to bring the temperature of the fluid down to the desiredlevel. In a seven electrode embodiment where 150 W is being supplied tothe electrodes 506, for example, a suitable constant fluid flow rate isabout 5 ml/min to about 20 ml/min.

Although the present inventions are not limited to any particular typeor number, the exemplary probe 500 includes seven spaced electrodes 506.The spaced electrodes 506 are preferably in the form of wound, spiralclosed coils. The coils are made of electrically conducting material,like copper alloy, platinum, or stainless steel, or compositions such asdrawn-filled tubing (e.g. a copper core with a platinum jacket). Theelectrically conducting material of the coils can be further coated withplatinum-iridium or gold to improve its conduction properties andbiocompatibility. Preferred coil electrodes are disclosed in U.S. Pat.Nos. 5,797,905 and 6,245,068.

Alternatively, the electrodes 506 may be in the form of solid rings ofconductive material, like platinum, or can comprise a conductivematerial, like platinum-iridium or gold, coated upon the device usingconventional coating techniques or an ion beam assisted deposition(IBAD) process. For better adherence, an undercoating of nickel, silveror titanium can be applied. The electrodes can also be in the form ofhelical ribbons. The electrodes can also be formed with a conductive inkcompound that is pad printed onto a non-conductive tubular body. Apreferred conductive ink compound is a silver-based flexible adhesiveconductive ink (polyurethane binder), however other metal-based adhesiveconductive inks such as platinum-based, gold-based, copper-based, etc.,may also be used to form electrodes. Such inks are more flexible thanepoxy-based inks. Open coil electrodes may also be employed.

The exemplary flexible electrodes 506 are preferably about 4 mm to about20 mm in length. In the preferred embodiments, the electrodes are 12.5mm in length with 1 mm to 3 mm spacing, which will result in an energytransmission region that is about 1 cm to about 14 cm in length and thecreation of continuous lesion patterns in tissue when coagulation energyis applied simultaneously to adjacent electrodes. For rigid electrodes,the length of the each electrode can vary from about 2 mm to about 10mm. Using multiple rigid electrodes longer than about 10 mm eachadversely effects the overall flexibility of the device, whileelectrodes having lengths of less than about 2 mm do not consistentlyform the desired continuous lesion patterns.

The electrodes 506 are electrically coupled to individual power wires538 that pass from the power wire lumen 526, and through a power wiretube 540, to a PC board or other suitable connector that is associatedwith a slot 542 in the handle 504. A plurality of temperature sensors544, such as thermocouples or thermistors, may be located on, under,abutting the longitudinal end edges of, or in between, the electrodes506. A reference thermocouple (not shown) may also be provided. In theexemplary implementation, temperature sensors 544 are located at bothlongitudinal ends of each electrode 506. The temperature sensors 544 areconnected to the PC board by signal wires 546, which pass through thesignal wire lumen 528 and a signal wire tube 548. The temperaturesensors 544 are also located within a linear channel 550 that is formedin the non-conductive outer structure 518. The linear channel 550insures that the temperature sensors will all face in the same direction(e.g. facing tissue) and be arranged in linear fashion. Preferably, theprobe 500 will be secured to the insulation element 600 in such a mannerthat the temperature sensors 544 and linear channel 550 will be alignedwith the slot 604 and will face tissue during use.

Additional details concerning fluid cooled surgical probes similar tothat described above are presented in U.S. Patent App. Pub. No.2003/0078644, which is entitled “Apparatus for Supporting Diagnostic andTherapeutic Elements in Contact With Tissue Including Dual Lumen CoolingDevice” and incorporated herein by reference.

Although the inventions disclosed herein have been described in terms ofthe preferred embodiments above, numerous modifications and/or additionsto the above-described preferred embodiments would be readily apparentto one skilled in the art. By way of example, but not limitation, thepresent inventions include systems that comprise one or both of a fluidsupply and control apparatus and a power supply and control apparatus inaddition to the various apparatus and/or clamps claimed below. It isintended that the scope of the present inventions extend to all suchmodifications and/or additions and that the scope of the presentinventions is limited solely by the claims set forth below.

1. An apparatus for use with a clamp including first and second clamp members, the apparatus comprising: amounting device configured to be removably secured to at least one of the first and second clamp members; a longitudinally extending insulation element associated with the mounting device; and a longitudinally extending lesion formation region, defining a length and a width that is substantially less than the width, associated with the insulation element such that there are insulation element side portions on opposite sides of the lesion formation region defining respective side portion widths that are greater than the lesion formation region width.
 2. An apparatus as claimed in claim 1, wherein the lesion formation region comprises a slot.
 3. An apparatus as claimed in claim 2, wherein the lesion formation region further comprises an energy transmission element aligned with at least a portion of the slot.
 4. An apparatus as claimed in claim 3, wherein the energy transmission element comprises a porous, electrically non-conductive structure configured to retain ionic fluid.
 5. An apparatus as claimed in claim 3, further comprising: an energy emission element aligned with at least a portion of the slot.
 6. An apparatus as claimed in claim 5, wherein the energy emission element comprises an electrode.
 7. An apparatus as claimed in claim 5, wherein the insulation element includes a fluid transmission space connected to the slot and at least a portion of the fluid transmission space is located between the energy emission element and the slot.
 8. An apparatus as claimed in claim 1, wherein the insulation element side portion widths are each one of twice the lesion formation region width, three times the lesion formation region width, four times the lesion formation region width, five times the lesion formation region width, six times the lesion formation region width, seven times the lesion formation region width, eight times the lesion formation region width, and nine times the lesion formation region width.
 9. A clamp, comprising: first and second clamp members; a longitudinally extending insulation element carried by one of the first and second clamp members; and a longitudinally extending lesion formation region, defining a length and a width that is substantially less than the width, associated with the insulation element such that there are insulation element side portions on opposite sides of the lesion formation region defining respective side portion widths that are greater than the lesion formation region width.
 10. A clamp as claimed in claim 9, wherein the lesion formation region comprises a slot.
 11. A clamp as claimed in claim 10, wherein the lesion formation region further comprises an energy transmission element aligned with at least a portion of the slot.
 12. A clamp as claimed in claim 11, wherein the energy transmission element comprises a porous, electrically non-conductive structure configured to retain ionic fluid.
 13. A clamp as claimed in claim 11, further comprising: an energy emission element aligned with at least a portion of the slot.
 14. A clamp as claimed in claim 13, wherein the energy emission element comprises an electrode.
 15. A clamp as claimed in claim 13, wherein the insulation element includes a fluid transmission space connected to the slot and at least a portion of the fluid transmission space is located between the energy emission element and the slot.
 16. A clamp as claimed in claim 9, wherein the insulation element side portion widths are each one of twice the lesion formation region width, three times the lesion formation region width, four times the lesion formation region width, five times the lesion formation region width, six times the lesion formation region width, seven times the lesion formation region width, eight times the lesion formation region width, and nine times the lesion formation region width.
 17. A method of forming a lesion in a target tissue structure that is in the vicinity of a non-target tissue structure, comprising: positioning a lesion formation region and an insulation region that extends laterally from the lesion formation region on a first side the target tissue structure with a first clamp member such that the lesion formation region is aligned with target tissue and the insulation region extends substantially to the non-target tissue structure; and forming a lesion in the target tissue structure with the lesion formation region.
 18. A method as claimed in claim 17, wherein positioning a lesion formation region and an insulation region comprises positioning a lesion formation region and an insulation region that extends laterally from the lesion formation region with a first clamp member such that the lesion formation region is aligned with atrial tissue and the insulation region extends substantially to at least one pulmonary vein.
 19. A method as claimed in claim 17, wherein forming a lesion comprises directing lesion formation energy through an energy transmission element and into the target tissue structure.
 20. A method as claimed in claim 17, wherein forming a lesion comprises directing radio-frequency energy from an electrode through an energy transmission element and into the target tissue structure. 